Centrifuge with coated weir plates

ABSTRACT

A decanter centrifuge, for separating a sludge into components, with a rotor and a scroll arranged inside the rotor. The rotor is configured at least partially as a solid bowl rotor with at least a cylindrical section and a conical section. The rotor includes a first end face, concluding the cylindrical section of the rotor, with a first diameter, and a second end face, concluding the conical section, with a second smaller diameter. A flange with one or multiple openings is arranged on the first end face, wherein one or multiple weir plates are fastened to the flange which at least partially cover the openings and are arranged to set a liquid level inside the rotor and form a first radial outlet edge for letting out a liquid at the first end face. The weir plates include an elastically deformable coating on their side facing the flange.

The invention relates to a centrifuge, in particular a decantercentrifuge, for separating a sludge into multiple components, with arotor and a scroll arranged inside the rotor, wherein the rotor isconfigured at least partially as a solid bowl rotor with at least acylindrical section and a conical section, wherein the rotor comprises afirst end face, concluding the cylindrical section of the rotor, with afirst diameter, and a second end face, concluding the conical section,with a second smaller diameter, wherein a flange with one or multipleopenings is arranged on the first end face, wherein one or multiple weirplates are fastened to the flange, which plates at least partially coverthe openings and are arranged inside the rotor to set a liquid level andform a first radial outlet edge for letting out a liquid at the firstend face.

Such types of centrifuges are known. It has been shown to bedisadvantageous that breeding places for bacteria can form in thecontact region between the weir plate and the rotor. Such types ofcentrifuges known from the prior art therefore do not find use inapplications in which hygienic cleanliness is required.

The object of the invention is therefore to provide a centrifuge whichcan be used in hygiene applications.

This object is achieved according to the invention by means of acentrifuge according to claim 1. Advantageous further developments ofthe invention are specified in the dependent claims.

It is particularly advantageous in the centrifuge, in particular adecanting centrifuge for separating a sludge into multiple components,with a rotor and a scroll arranged inside the rotor, wherein the rotoris configured at least partially as a solid bowl rotor with at least acylindrical section and a conical section, wherein the rotor comprises afirst end face, concluding the cylindrical section of the rotor, with afirst diameter, and a second end face concluding the conical sectionwith a second smaller diameter, wherein a flange with one or multipleopenings is arranged on the first end face, wherein one or multiple weirplates are fastened on the flange, which plates at least partially coverthe openings and are arranged to set a liquid level inside the rotor andform a first radial outlet edge for letting out a liquid on a first endface, that the weir plates at least partially comprise an elasticallydeformable coating on their side facing the flange.

The weir plates which at least partially comprise an elasticallydeformable coating on their side facing the flange serve to avoid a gapformation and thus for the sealing between the rotor and the weirplates. In the fastening of the weir plates to the flange, the coatingis squeezed between the weir plates and the flange, due to its elasticdeformability, so that possible gaps between the weir plates and theflange are closed off. In this way, possible gaps forming between theweir plates and the flange is prevented, which gaps can function asbreeding grounds for bacteria, which can contaminate the liquid to bedischarged via the first end face. A centrifuge according to theinvention is thus employable in hygienic applications, for example inthe foodstuffs industry, without here taking the risk of acontamination.

In particular, separation into two components can occur, in particular asolid matter part, with is transported away at the second end face ofthe rotor, and a liquid part, which is transported away at the first endface of the rotor.

Here, a solid bowl centrifuge, a decanter centrifuge or a screen bowlcentrifuge with a pre-thickening can be concerned.

Decanter centrifuges work according to the so-called counterflowprinciple. The sludge to be separated is placed roughly into the middleof the rotor. The sedimented solid matter is conveyed by the scrollcirculating with a differential speed to the rotor in the directiontowards the small diameter and thus to the second end face, while theclarified liquid overflows over the flange at the first end face of therotor.

The liquid level determines the ratio between the clarified part and thedry part of the rotor. The liquid level here defines the level of liquidwhich results in the treatment of the sludge by means of a rotation ofthe rotor. The liquid level can also be referred to as sump level, theclarified part as sump and the dry part as dry beach. Here, the dry partstarts in the conical section of the rotor, depending on the position ofthe weir plates, and ends with the second end face of the rotor at thesmaller diameter of the rotor. The clarified part is thus the part ofthe rotor in which a level of liquid is present. The dry part of therotor thus stars at the first end face of the rotor and ends at the drypart of the rotor. The differential speed between the scroll and therotor is usually realized by a high-power drive, in particular viaV-belts.

The screen bowl centrifuge with pre-thickening generally relates to aprecedingly described decanting centrifuge in which, adjacent to thesecond end face of the rotor, a section of the rotor or a further rotoris connected, which is configured as a screen rotor, so that liquid, inparticular with small solid matter particles, can flow out via itsscreen jacket. Larger solid matter particles are here furthertransported, by means of the scroll, to the free end face of the screenrotor and transported away to the free edge of the screen rotor. Thefree end face of the screen rotor here refers to end face of the screenrotor facing away from the conical section of the rotor. In such acentrifuge, a separation of the sludge into three components can thusoccur: liquid via the first end face, smaller solid matter with liquidvia the screen jacket of the screen rotor, and larger solid matter viathe free end face of the screen rotor. In particular, further rotors arethus possible adjacent to the second end face of the rotor.

In the solid bowl centrifuge, the rotor is at least partially configuredas a solid bowl rotor.

The elastically deformable coating, which is arranged at least on theside of the weir plates facing to the flange, serves to avoid a gapformation, and thus to the sealing between the rotor and the weirplates. In the fastening of the weir plates to the flange, the coatingis squeezed between the weir plates and the flange due to its elasticdeformability, so that possible gaps between the weir plates and theflange are closed off. In this way, the forming of possible gaps betweenthe weir plates and the flange are prevented, which gaps can act asbreeding grounds for bacteria, which can contaminate the liquid to bedischarged via the first end face. A centrifuge according to theinvention can thus find use in hygienic applications, for example in thefoodstuffs industry, without taking a risk of a contamination here.

A reversible deformability of the coat is meant with the elasticdeformability. With the second smaller diameter at the second end faceof the rotor, it is meant that the second diameter is smaller incomparison to the first diameter at the first end face of the rotorcorresponding to the conical course of the conical section taperingtowards the second end face.

In particular, the rotor can be positioned in such a manner that itsrotational axis is oriented horizontally or at any angle to thehorizontal.

In particular, the flange can here merely comprise one opening. In thiscase, only one weir plate would be arranged. Preferably, the flangecomprises n in particular equally distributed openings over itscircumference, wherein n is an integer greater than 1, however.

In particular, the weir plates can respectively comprise a coating whichrespectively fully sheathes to weir plates.

In particular, the cylindrical section and the conical section of therotor can be configured as a solid bowl rotor.

In particular, such a type of centrifuge can further comprise a driveunit for rotary and/or oscillating movement of the rotor and the scrollrunning inside the rotor. In particular, such a type of centrifuge canfurther comprise at least one housing and/or at least one line fortransporting the sludge into the rotor and/or at least one washing linefor introducing a washing solution, in particular an acid and/or a base,into the rotor and/or at least respectively one container for collectingthe matter separated by the centrifuge.

The weir plates preferably comprise the elastically deformable coatingat least in a contact region with the flange. The contact region heredescribes the surfaces of the weir plates and of the flange which, afterthe fixing of the weir plates, rest on one another or, put another way,would be in contact. An effective prevention of the gap formation ishereby possible without fully coating the weir plate, in particular theside of the weir plates facing the flange.

Preferably, the coating consists at least partially of a plasticmaterial. A plastic material coating can thus be concerned as thecoating. In particular, the coating can be produced from a hybridmaterial, wherein at least a part of the material consists of a plasticmaterial. Plastic materials essentially distinguish themselves through acertain elastic deformability.

The coating preferably consists of an elastomer, in particular ofsynthetic rubber, in particular of nitrile rubber and/or ofethylene-propylene-diene rubber. The coating thus preferably consists ofelastomer, in particular of synthetic rubber, in particular ofacrylonitrile butadiene rubber, also referred to as nitrile rubber,and/or of ethylene-propylene-diene rubber, also referred to as EPDM:ethylene-propylene-diene; M-class. Such elastomers distinguishthemselves by a high elastic deformability with simultaneously presenttensile strength.

The coating is preferably antibacterial and/or antimicrobial. To thatend, the coating can in particular consist partially of silver and/orsilver ions. In particular, silver and/or silver ions can be integratedin the material matrix of the coating. An avoidance of bacteria isthereby improved.

The flange is preferably formed integrally with the rotor. This can inparticular occur through casting and/or flanging of the rotor and/orwelding of the flange to the rotor.

Alternatively, the flange and the rotor can be configured in amulti-part manner, the flange and the rotor can in particular beforce-fittingly and/or integrally and/or form-fittingly connected withone another, in particular by means of a screw connection and/or ariveting.

The weir plates are preferably fixable to the flange in multipledifferent positions, in particular adjustably and fixable to the flange.Depending on a desired liquid level inside the rotor, the weir platescan thus be fixed, in a radial direction of the flange, in differentpositions. In this way, the position of the first radial outlet edge onthe radial course of the flange can be adjusted. The liquid level isthereby flexibly settable and can be optimally adapted, depending uponseparation task and/or the features of the sludge to be treated.

The weir plates are preferably adjustable in a continuous or stepwisemanner and fixable to the flange. Depending on desired liquid levelinside the rotor, the weir plates can thus be adjusted to differentpositions in the radial direction of the flange and fixed to the flange.In this way, the position of the first radial outlet edge on the radialcourse of the flange can be adjusted. The parameters of the centrifugeare thereby flexible and can be optimally adapted depending onseparation task.

To that end, the flange can in particular comprise multiple threadedbores at different heights with respect to the radial course of theflange, wherein fastening screws can be screwed into the threaded bores,by means of which the weir plates are fixable. Depending on desiredliquid level inside the rotor, the weir plates can thus be fixed, in astepwise manner, in higher positioned or lower positioned threaded boresby means of the fastening screws. A threaded bore displaced along thediameter in a direction towards the circle center of the flange,relative to a lower positioned threaded bore, is referred to with theterm “a higher positioned threaded bore”.

Alternatively, the weir plates can also be adjustable in a continuousmanner. For example, the weir plates can comprise elongate holes to thatend, through which fastening screws engage through and fix the weirplates at the desired height. Alternatively, the weir plates can per secomprise one or multiple openings for continuous adjustment, whichopenings, depending on positioning of the weir plates, in particular therotation thereof, form a higher or a lower outlet edge and thus make ahigher or lower liquid level inside the rotor possible.

The rotor and/or weir plates preferably consist of a metal, inparticular of a metal alloy. A firm fixing with a high bearing capacitycan thereby be ensured.

The coating is preferably form-fittingly and/or force-fittingly and/orintegrally connected with the weir plate(s). What is meant is thatrespectively one coating occurs per respective weir plate. A firmconnection between coating and weir plate is important, as great forcesare exerted thereupon in the operation of the centrifuge. In particular,a press-fit/interference-fit and/or an adhering between the coating andthe weir plate can occur.

The coating is preferably produced by means of a plastic materialencapsulation of the respective weir plates. A particularly firmconnection with the weir plates and a high reproducibility are therebymade possible.

The weir plates preferably respectively comprise at least one negativeprofile, which interacts with a corresponding positive profile of thecoating, in particular in that a press-fit exists between the profiles.In particular, the respective weir plate and the coating canrespectively comprise multiple such profiles.

The weir plates preferably respectively comprise at least one positiveprofile, which interacts with a corresponding negative profile of thecoating, in particular in that a press-fit exists between the profiles.In particular, the respective weir plate and the coating canrespectively comprise multiple such profiles.

The weir plates are preferably respectively fastened to the flange bymeans of fastening elements, which engage through at least onethrough-hole of the weir plate, wherein the coating comprises aperforation in a region surrounding the through-hole so that, in thisregion surrounding the through-hole, a direct contact exists between theweir plates and the flange. By means of such a perforation of thecoating, it is ensured that a load-bearing connection, in particularscrew connection, is possible between the weir plates and the flange.The bearing capacity is possible in that simply no coating is present inthis region so that, in this region, the weir plate and/or the weirplates abut(s) directly on the flange, so that actually no elasticallydeformable coating is disposed therebetween.

Alternatively or cumulatively, the coating can comprise such types ofperforations on the side of the weir plate facing away from the flange,so that a direct contact exists between the fastening elements and theweir plate in the region surrounding the through-hole.

An exemplary embodiment of the invention is illustrated in the figures.They show:

FIG. 1 a partial view of a cross section through a centrifuge accordingto the invention, with weir plates, in a first radial position;

FIG. 2 a partial view of a cross section through a centrifuge accordingto the invention, with weir plates, in a second radial position;

FIG. 3 a perspective view of a weir plate on a flange;

FIG. 4 a perspective view of the weir plate according to FIG. 3.

Identical components and assemblies are referred to in the figures withthe same reference characters.

FIG. 1 shows a partial view of a cross section through a centrifugeaccording to the invention. Here, a rotor with a cylindrical section 2and a conical section 3 is discernable, wherein the rotor is rotatablymounted in a housing 10. Inside the rotor, a scroll 4 with a pluralityof scroll threads 40 is also rotatably mounted. Here, the rotorcomprises a first end face 6 which is located left at the drawing plane.Right at the drawing plane, the rotor further comprises a second endface 5, which comprises a smaller diameter relative to the first endface 6. The rotational axis of the rotor not discernable in FIG. 1 isoriented horizontally.

A flange 8 is arranged on the end face 6 of the rotor and is fastened bymeans of multiple screws 80. The flange 8 comprises multiple openings 83uniformly distributed over its circumference. Multiple weir plates 7 arefurther fastened, by means of screws 71, to the flange 8, distributedover its circumference, which plates partially cover the openings 83.Due to the fact that the weir plates 7 partially cover the openings 83of the flange 8, the weir plates 7 define a first radial outlet edge 85for letting out a liquid at the first end face 6.

A level of liquid 9 thereby occurs inside the rotor during the treatmentof a sludge by means of the centrifuge. The treatment occurs in that therotor and the scroll 4 are rotated with a differential speed. Furtherrecognizable is a clarified part 90 of the rotor, in which the liquidaccumulates, and the solid matter part 91 of the rotor, in which theseparated solid matter is located inside rotor and is continuouslytransported away via the second end face 5 by means of the scrollthreads 40. The clarified part 90 can further be referred to as sump,and the solid matter part 91 as dry beach. Accordingly, the liquid isled away out of the rotor via the outlet edge 85 defined at the imageplane at the left end face 6 by the correspondingly positioned weirplates 7.

The weir plates 7 are adjustable, with respect to their radial height,with respect to the radial course of the flange 8 and fixable to theflange 8 by means of the screws 71. To that end, the flange 8 comprisesmultiple threaded bores corresponding to the screws 71, which bores arearranged distributed in its radial course. Via the adjustment of theweir plates 7, the radial position of the outlet edge 85 and thus theliquid level 9 inside the rotor can be set. Further, the weir plates 7,on their side facing to the flanges 8, comprise an elasticallydeformable coating from an elastomer, which is not discernable inFIG. 1. The coating prevents a gap formation between the flange 8 andthe weir plates 7, so that no bacteria can nest therein. Such acentrifuge can thereby also find use in hygienic applications, inparticular in the foodstuffs industry.

FIG. 2 shows an arrangement according to FIG. 1, wherein it isdiscernable that the weir plates 8 were adjusted to a radially higherlevel, so that the level of liquid 9 is higher than in the illustrationaccording to FIG. 1. In this way, the clarified part 90 is largerrelative to the illustration from FIG. 1, whereas the dry part 91 issmaller.

Through the possibility of the radially variable positioning of the weirplates 7 on the flange 8, the centrifuge can be adapted to theoperational requirements, as the ratio of clarified part 90 and dry part91 is hereby likewise variably adaptable.

FIG. 3 shows a perspective view of a weir plate 7 which is arranged onthe flange 8. The weir plate 7 here partially covers the opening 83 ofthe flange 8. The weir plate 7 is here fastened to the flange by meansof four screws 71. To that end, the screws 71 are screwed in threadedbores 82 of the flange 8. Further, a coating 70 of the weir plate 7 isdiscernable, which coating was squeezed between the weir plate 7 and theflange 8 after the fastening of the weir plate 7 by means of the screws71. In this way, the coating 70 squeezed between the weir plate 7 andthe flange 8 prevents gaps from forming between these elements, in whichgaps breeding grounds for bacteria can come about.

FIG. 4 shows a perspective view of the weir plate 7 according to FIG. 3,wherein the side of the weir plate 7 facing the flange is illustrated.It is recognizable that the coating 70 comprises perforations 73 aroundthe region of the through-holes 72 of the weir plate 7. Theseperforations 73 serve to achieve a load-bearing connection between theweir plate 7 and the flange 8 in that the regions around thethrough-holes 72 are free of a coating 70. In this way, the weir plate 7and the flange 8 lie directly on top of one another in the regionsaround the through-holes 72, so that a load-bearing connection betweenthe two components is made possible.

1.-14. (canceled)
 15. A centrifuge, in particular a decanter centrifuge,for separating a sludge into multiple components, with a rotor and ascroll arranged inside the rotor, wherein the rotor is configured atleast partially as a solid bowl rotor with at least a cylindricalsection and a conical section, wherein the rotor comprises a first endface, concluding the cylindrical section of the rotor, with a firstdiameter, and a second end face, concluding the conical section, with asecond smaller diameter, wherein a flange with one or multiple openingsis arranged at the first end face, wherein one or multiple weir platesare fastened to the flange, which at least partially cover the openingsand are arranged to set a liquid level inside the rotor and form a firstradial outlet edge for letting out a liquid at the first end face,wherein the weir plates at least partially comprise an elasticallydeformable coating on their side facing to the flange.
 16. Thecentrifuge according to claim 15, wherein the weir plates comprise theelastically deformable coating, at least in one contact region with theflange.
 17. The centrifuge according to claim 15, wherein the coating atleast partially consists of a plastic material.
 18. The centrifugeaccording to claim 15, wherein the coating consists of an elastomer, inparticular of synthetic rubber, in particular of nitrile rubber and/orof ethylene-propylene-diene rubber.
 19. The centrifuge according toclaim 15, wherein the coating is antibacterial and/or antimicrobial. 20.The centrifuge according to claim 15, wherein the flange is formedintegrally with the rotor.
 21. The centrifuge according to claim 15,wherein the weir plates are fixable to the flange in multiple differentpositions.
 22. The centrifuge according to claim 15, wherein the weirplates are adjustable in a continuous or stepwise manner and are fixableto the flange.
 23. The centrifuge according to claim 15, wherein therotor and/or weir plates consist of a metal, in particular of a metalalloy.
 24. The centrifuge according to claim 15, wherein the coating isform-fittingly and/or force-fittingly and/or integrally connected withthe weir plates.
 25. The centrifuge according to claim 15, wherein thecoating is produced by means of a plastic material encapsulation of therespective weir plates.
 26. The centrifuge according to claim 15,wherein the weir plates respectively comprise at least one negativeprofile, which interacts with a corresponding positive profile of thecoating, in particular in that a press-fit exists between the profiles.27. The centrifuge according to claim 15, wherein the weir platesrespectively comprise at least one positive profile, which interactswith a corresponding negative profile of the coating, in particular inthat a press-fit exists between the profiles.
 28. The centrifugeaccording to claim 15, wherein the weir plates are respectively fastenedto the flange by means of fastening elements, which engage through atleast one through-hole of the weir plate, wherein the coating comprisesa perforation in a region surrounding the through-hole, so that a directcontact between the weir plates and the flange exists in this regionsurrounding the through-hole.